The present invention relates generally to power generation equipment, and more particularly to improved fluid passages for solid oxide fuel cells.
A high temperature, solid oxide fuel cell (hereinafter “SOFC”) stack is typically constructed of an array of axially-elongated tubular-shaped connected SOFCs and associated fuel and air distribution equipment. In addition, typical alternative constructions to the tubular SOFC are planar cross flow fuel cells, counterflow fuel cells and parallel flow fuel cells which are constructed from flat single cell members. Such members typically comprise trilayer anode/electrolyte/cathode components which conduct current from cell to cell and provide channels for gas flow into a cubic structure or stack.
SOFCs generate electrical energy through electrochemical reactions between an oxidant and hydrocarbon fuel gas to produce a flow of electrons in an external circuit. In addition, SOFCs generate waste heat that is typically removed via an oxidant in order to maintain a desired temperature level of SOFC components such as the anode, cathode and electrolyte.
While SOFCs have demonstrated the potential for high efficiency and low pollution in power generation, some problems remain associated with temperature regulation of the components in SOFCs. SOFCs typically comprise cooling channels (in alternating flat single cell sections) or riser tubes (in tubular SOFCs) in which the oxidant, typically air, is used to aid in the transfer or removal of the waste heat so as to maintain the stack temperature at or below prescribed limits and maintain a predetermined thermal gradient in the SOFC. Such channels or riser tubes; however, typically comprise smooth surfaces having the undesired characteristic of providing low thermal transfer coefficients between the channel or tube surface and the oxidant.
Accordingly, there is a need in the art for a SOFC having improved fluid passages that provide improved heat transfer characteristics.